serial_recovery: Replace CBOR decoding code with generated code

 - Add the cddl_gen repository as a submodule.
 - Add a CDDL description file for the serial recovery packets to be
   decoded.
 - Add generated code files and cddl_gen's CBOR library to CMakeList.txt
   for Zephyr.
 - Convert boot_serial.c to use the new code.
 - Add a bash script to (re)generate code files using cddl_gen.py.

Serial recovery should work exactly as before, but the binary should be
about 1k smaller.

Signed-off-by: Øyvind Rønningstad <oyvind.ronningstad@nordicsemi.no>

Author: oyvindronningstad

.gitmodules

@@ -16,3 +16,6 @@
 [submodule "boot/cypress/libs/cy-mbedtls-acceleration"]
 	path = boot/cypress/libs/cy-mbedtls-acceleration
 	url = https://github.com/cypresssemiconductorco/cy-mbedtls-acceleration.git
+[submodule "boot/boot_serial/src/cddl_gen"]
+	path = ext/cddl_gen
+	url = https://github.com/oyvindronningstad/cddl_gen.git

boot/boot_serial/src/boot_serial.c

@@ -43,7 +43,6 @@
 #include <crc/crc16.h>
 #include <base64/base64.h>
 #include <tinycbor/cbor.h>
-#include <tinycbor/cbor_buf_reader.h>
 #endif /* __ZEPHYR__ */
 
 #include <flash_map_backend/flash_map_backend.h>
@@ -60,6 +59,8 @@
 #include "bootutil_priv.h"
 #endif
 
+#include "serial_recovery_cbor.h"
+
 MCUBOOT_LOG_MODULE_DECLARE(mcuboot);
 
 #define BOOT_SERIAL_INPUT_MAX   512
@@ -226,26 +227,20 @@ bs_list(char *buf, int len)
 static void
 bs_upload(char *buf, int len)
 {
-    CborParser parser;
-    struct cbor_buf_reader reader;
-    struct CborValue root_value;
-    struct CborValue value;
-    uint8_t img_data[512];
+    const uint8_t *img_data = NULL;
     long long int off = UINT_MAX;
     size_t img_blen = 0;
     uint8_t rem_bytes;
     long long int data_len = UINT_MAX;
     int img_num;
     size_t slen;
-    char name_str[8];
     const struct flash_area *fap = NULL;
     int rc;
 #ifdef CONFIG_BOOT_ERASE_PROGRESSIVELY
     static off_t off_last = -1;
     struct flash_sector sector;
 #endif
 
-    memset(img_data, 0, sizeof(img_data));
     img_num = 0;
 
     /*
@@ -258,99 +253,36 @@ bs_upload(char *buf, int len)
      * }
      */
 
-    /*
-     * Object comes within { ... }
-     */
-    cbor_buf_reader_init(&reader, (uint8_t *)buf, len);
-    cbor_parser_init(&reader.r, 0, &parser, &root_value);
-
-    if (!cbor_value_is_container(&root_value)) {
-        goto out_invalid_data;
-    }
-    if (cbor_value_enter_container(&root_value, &value)) {
+    Upload_t upload;
+    if (!cbor_decode_Upload((const uint8_t *)buf, len, &upload)) {
         goto out_invalid_data;
     }
-    while (cbor_value_is_valid(&value)) {
-        /*
-         * Decode key.
-         */
-        if (cbor_value_calculate_string_length(&value, &slen)) {
-            goto out_invalid_data;
-        }
-        if (!cbor_value_is_text_string(&value) ||
-            slen >= sizeof(name_str) - 1) {
-            goto out_invalid_data;
-        }
-        if (cbor_value_copy_text_string(&value, name_str, &slen, &value)) {
-            goto out_invalid_data;
-        }
-        name_str[slen] = '\0';
-        if (!strcmp(name_str, "data")) {
-            /*
-             * Image data
-             */
-            if (value.type != CborByteStringType) {
-                goto out_invalid_data;
-            }
-            if (cbor_value_calculate_string_length(&value, &slen) ||
-                slen >= sizeof(img_data)) {
-                goto out_invalid_data;
-            }
-            if (cbor_value_copy_byte_string(&value, img_data, &slen, &value)) {
-                goto out_invalid_data;
-            }
-            img_blen = slen;
-        } else if (!strcmp(name_str, "off")) {
-            /*
-             * Offset of the data.
-             */
-            if (value.type != CborIntegerType) {
-                goto out_invalid_data;
-            }
-            if (cbor_value_get_int64(&value, &off)) {
-                goto out_invalid_data;
-            }
-            if (cbor_value_advance(&value)) {
-                goto out_invalid_data;
-            }
-        } else if (!strcmp(name_str, "len")) {
-            /*
-             * Length of the image. This should only be present in the first
-             * block of data; when offset is 0.
-             */
-            if (value.type != CborIntegerType) {
-                goto out_invalid_data;
-            }
-            if (cbor_value_get_int64(&value, &data_len)) {
-                goto out_invalid_data;
-            }
-            if (cbor_value_advance(&value)) {
-                goto out_invalid_data;
-            }
-        } else if (!strcmp(name_str, "image")) {
-            /*
-             * In a multi-image system, image number to upload to, if not
-             * present will upload to slot 0 of image set 0.
-             */
-            if (value.type != CborIntegerType) {
-                goto out_invalid_data;
-            }
-            if (cbor_value_get_int(&value, &img_num)) {
-                goto out_invalid_data;
-            }
-            if (cbor_value_advance(&value)) {
-                goto out_invalid_data;
-            }
-        } else {
-            /*
-             * Unknown keys.
-             */
-            if (cbor_value_advance(&value)) {
-                goto out_invalid_data;
-            }
+
+    for (int i = 0; i < upload._Upload_members_count; i++) {
+        _Member_t *member = &upload._Upload_members[i];
+        switch(member->_Member_choice) {
+            case _Member_image:
+                img_num = member->_Member_image;
+                break;
+            case _Member_data:
+                img_data = member->_Member_data.value;
+                slen = member->_Member_data.len;
+                img_blen = slen;
+                break;
+            case _Member_len:
+                data_len = member->_Member_len;
+                break;
+            case _Member_off:
+                off = member->_Member_off;
+                break;
+            case _Member_sha:
+            default:
+                /* Nothing to do. */
+                break;
         }
     }
-    if (off == UINT_MAX) {
+
+    if (off == UINT_MAX || img_data == NULL) {
         /*
          * Offset must be set in every block.
          */

boot/boot_serial/src/regenerate_serial_recovery_cbor.sh

@@ -0,0 +1,44 @@
+#!/bin/bash
+
+if [ "$1" == "--help" ] || [ "$1" == "" ]; then
+	echo "Regenerate serial_recovery_cbor.c|h if the cddl_gen submodule is updated."
+	echo "Usage: $0 <copyright>"
+	echo "  e.g. $0 \"2020 Nordic Semiconductor ASA\""
+	exit -1
+fi
+
+add_copy_notice() {
+echo "$(printf '/*
+ * This file has been %s from the cddl_gen submodule.
+ * Commit %s
+ */
+
+' "$2" "$(git -C ../../../ext/cddl_gen rev-parse HEAD)"; cat $1;)" > $1
+}
+
+echo "Copying cbor_decode.c|h"
+copy_with_copy_notice() {
+	cp $1 $2
+	add_copy_notice $2 "copied"
+}
+
+copy_with_copy_notice ../../../ext/cddl_gen/src/cbor_decode.c cbor_decode.c
+copy_with_copy_notice ../../../ext/cddl_gen/include/cbor_decode.h cbor_decode.h cbor_decode.h
+
+echo "Generating serial_recovery_cbor.c|h"
+python3 ../../../ext/cddl_gen/scripts/cddl_gen.py -i serial_recovery.cddl -t Upload --oc serial_recovery_cbor.c --oh serial_recovery_cbor.h --time-header
+
+add_copyright() {
+echo "$(printf '/*
+ * Copyright (c) %s
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+' "$2"; cat $1;)" > $1
+}
+
+add_copyright serial_recovery_cbor.c "$1"
+add_copyright serial_recovery_cbor.h "$1"
+add_copy_notice serial_recovery_cbor.c "generated"
+add_copy_notice serial_recovery_cbor.h "generated"

boot/boot_serial/src/serial_recovery.cddl

@@ -0,0 +1,15 @@
+;
+; Copyright (c) 2020 Nordic Semiconductor ASA
+;
+; SPDX-License-Identifier: Apache-2.0
+;
+
+Member = ("image" => int) /
+	("data" => bstr) /
+	("len" => int) /
+	("off" => int) /
+	("sha" => bstr)
+
+Upload = {
+	3**5members: Member
+}

boot/zephyr/CMakeLists.txt

@@ -191,6 +191,8 @@ endif()
 if(CONFIG_MCUBOOT_SERIAL)
   zephyr_sources(${BOOT_DIR}/zephyr/serial_adapter.c)
   zephyr_sources(${BOOT_DIR}/boot_serial/src/boot_serial.c)
+  zephyr_sources(${BOOT_DIR}/boot_serial/src/serial_recovery_cbor.c)
+  zephyr_sources(${BOOT_DIR}/boot_serial/src/cbor_decode.c)
 
   zephyr_include_directories(${BOOT_DIR}/bootutil/include)
   zephyr_include_directories(${BOOT_DIR}/boot_serial/include)